Insecticidal compounds



Patented Sept. 29, 1953 UNITED STATES PATENT OFFICE 2,653,896INSECTICIDAL COMPOUNDS Edward B. Hodge, Terre Haute, Ind., assignor toCommercial Solvents Corporation, Terre Haute, 11111., a corporation ofMaryland No Drawing. Application February 10, 1951, Serial No. 210,432

6 Claims. 1

wherein R is an alkyl chain selected from the group CH3 and CzHs, asactive ingredients in such compositions.

Many materials and classes of materials have in the past beenrecommended as insecticides,

fungicides, pesticides, and the like. A great majority of these,however, have been impractical for various reasons due to availability,cost, impractical physical characteristics such as odor, undesirableeifects on the hosts or other objects with which the product comes incontact, difliculty and danger of application, etc. Of equal if notgreater importance, is the high degree of selectivity possessed by manyproducts of this character. For example, a particular agent may beespecially efiective against one or two insects but have no harmfulaction whatsoever on any other when applied in practical quantities.Also, particular insects incline to be resistant to almost every kind ofinsecticidal compound of practical utility known. Even closely relatedchemical compounds often have widely diiferent effects upon both pestsand their host, with the result that a new material must be tested underconditions simulating those of actual use before its utility can bedetermined.

The efficacy of an insecticidal composition is most generally measuredin terms of per cent kill. It goes without saying that such measurementsmust be for a definite period of time, and that other conditions must becarefully controlled and standardized to permit comparisons of results.For flying insects, the efficacy may also be measured in terms of percent knockdown. Many prior art insecticides possess kill and knock-downcharacteristics in different degrees. For this reason, it may benecessary to combine two or more compounds in order to achieveeffectively both knock-down and kill. In general, an insecticidepossessing both properties in a high degree has greater utility thananother insecticide which is comparable in only one property.

I have now discovered that compounds having the general formula:

wherein R is an alkyl chain selected from the group CH3 and C2H5,possess strong insecticidal properties; and, in particular, that thesecompounds are especially effective killing agents for the house fly,southern army worm, Mexican bean beetle and pea aphid. I have alsodiscovered that not only do my new compounds produce a high per centkill, when used in low concentrations against flies; but also that theypossess excellent knock-down properties.

My invention comprises two compounds; namely,2-nitro-1-p-chlorophenyl-l-(2,4-dichlorophenyl) propane and2-nitro-l-p-chlorophenyl- 1 (ZA-dichlorophenyl) -butane.

The 2 nitro 1-p-chlorophenyl-l-(2,4-dichlorophenyl)-propane of myinvention can be prepared as follows: To a mixture of 163 g. ofchlorobenzene and 326 g. of 96% sulfuric acid was added 163 g. of2-nitro-1-(2,4-dichlorophenyl) -1propanol. This addition took minutesand the reaction mixture was stirred vigorously and cooled to 25 C. by acirculating water bath during the addition. After all the nitro alcoholhad been added stirring was continued for an additional 15 minutes. Thenthe oil layer was separated and washed with 200 ml. of 5% sodiumcarbonate solution. Then 400 ml. of water were added and the mixture wasdistilled to a vapor temperature of 99 C. On standing, the oil residuefrom. this distillation partially crystallized. It was mixed with 200m1. of petroleum ether and the solid thus obtained was recrystallizedfrom ethyl alcohol two times to give a product which melted at l03-l06C. The yield of Z-nitro-l-pchlorophenyl-l-(Zi chlorophenyl) propane was58%.

The Z-nitro-l- (2,4diohlorophenyl) -1-propanol used. in the abovecondensation was obtained by condensing ZA-dichlorobenzaldehyde withnitroethane. A convenient method for effecting this condensation is asfollows:

Four moles of ZA-dichlorobenzaldehyde was added with stirring to asolution of 440 g. of so- 3 dlum bisulfite with 2000 ml. of distilledwater and stirred at room temperatures for two hours. Simultaneously sixmoles of nitroethane was dissolved slowly in a solution of 180 g. ofsodium hydroxide in 800 ml. of water, which was cooled in an ice-saltbath.

These solutions were mixed and stirred at room temperature for twelvehours, then poured into aseparatory funnel. {The two layerswereseparated, the aqueous layer was extracted with ether, and the etherportion was added to the organic layer. The ether solution wasextractedwvith saturated sodium bisulfite solution until unreactedaldehyde was removed. The ether solution was then dried with anhydroussodium-sulfate and the ether evaporated. Conversion to 2-nitro-1-(ZA-dichlorophenyl) +1.-propanol -...was 92%.

The 2-nitrol-p-chlorophenyl-l- (2,47QiChIQI'O-y phenyD-butane can beprepared by condensing 2 ,nitro -yl- (2,4-dichlrophenyl) 1:bu tanolfollowing the same procedure as that given above for condensing 2 -nitro 1 (2,4.- dichlorophenyl)-1 propanol with chlorobenzene. ;Also,,vthe2-.nitro- 1-(2,4-dichlorophenyl)-lbutanol may be prepared bycondensation of 2,4-dichlorobenzaldehyde with l-nitropropane,substantially as described above for the ,preparation of 2-nitro-1-(2,4-dich1orophenyl) -,1-propanol.

The exact quantity ofvmy new. compound to be utilized in insecticidalcompositions will be found to vary rather widely and to a certain extentdepends upon the type of compositions inwhich the material is beingemployed, method of application, natureof the insect pest to-becontrolled, and other factors commonly encountered in-the'insecticidalart. --Since the materials are relatively insoluble in some of thecommon solvents, this factor must also be taken into consideration. Ingeneral, however, compositions contai-ningabout 2% by Weight,in-either-a liquid or=solicl carrier, give excellent results. F'orsomerequirements, stronger concentrations may be desirable up to a maximumof about 5% for rapid knock-down of flies.

in Tables I and II below are given the results of tests with my newcompounds against various insect pests at difierent concentrations. Eachentry in Tables I and II is an average of several replications. Thetesting procedure used for female house flies was substantially asfollows:

vsolutions of various concentrations were prepared by dissolving theactive agent in a solvent asa carrier. Adult flies reared in thelaboratories under controlled conditionswere introduced into sphericalcages. Each cage was then placed on a revolving, turn-table, and theflies subjected to an atomized spray under constant pressure until 1.0ml. was delivered per cage. Immediately after the flies in the cage weresprayed, they were transferred to an observation cage, in which theywere .maintained under constant conditions for 24 hours. At the end ofthat time the number of dead flies was counted.

FOr the Mexican bean beetle, and the southern army worm the followingprocedure was used: Difierent quantities of the active insecticidalagents were uniformly mixed with a solid inert carrier in the form ofafinely ground powder. The dust thus obtained was applied in 0.2 gramamountsto host plants to which the insects were thentransferred. Thehost plants utilized for these tests were cranberry beans. At the end of48 v hours'the percentage of dead insects was determined.

TABLE I 2 nitro 1 p chZorophenyl-l-(2,4-dichlorophenyl) butane AveragePercent Concentra- Insect tion of tcxicant Perqent Kill lTlies None 10.0125 (by volume).. 46 0.05 (by volume) None 0 0.125 (by weight) 660.25 (by weight) 100 0.50 (by weight) 100 one 6 0.25 (by weight) H... 930.50 (by weight) 100 TABLE II .2 nitro 1 p chlorophenyZ-l-(2,4-dichloro-Y f h fly p q lme -Percent0on- Avera ge Ins ect 2522,; of Pe '.Qc t Kill(by weight) Mexican Bean Beetle 0. 25 190 0 O. 50 86 Southern Army Worm0. 25 93 0 0. 50 93 The diluents used in insecticidal compositions,whether liquid or-solid are generally called carriers or vehicles. FOrmycompounds, many different carriers may be used. Effectiveconcentrations can be obtained with most common solvents for relativelylong-chain -nitroparaffin hydrocarbons. The upper limit of the possibleconcentration -in these solvents, however, will be below 5% in manycases, because my compounds are'relatively insoluble. -Household spraykerosene (Ultrasene) was usedas the carrier in the iiytests--reportedabove. Effective concentrations can be used in other "liquidcarriers'such as the lower aliphatic alcohols (methyl, ethyl, propyl,butyl) chlorinated hydrocarbons solvents (carbon tetrachloride,dichloromethane, trichloromethane) and aromatic hydrocarbons (benzene,xylene, toluene). Aqueous suspensions of 1% can be madeand are unusallyeffective in some cases. Also, aqueous emulsions can be advantageouslyused.

As a solid vehicle I can employ any of the formsof powdered magnesium oraluminum silicates which are commonly employed in insecticidalcompositions, such as pyrophyllite, bentonite, fuller-s earth,kieselguhr, kaolin and talc. In the tests reported above, except forflies, pyrophyllitewas employed as the carrier. When solid carriers areused, there is, of course, no limit to the obtainable concentrations.

In addition to either a liquid or solid carrier, other killing agentsmay be mixed with my compounds. Low solubilities may limit the use ofcertainadditionalagents in aliquid carrier; but, in general, mycompounds may be used in conjunction with killing agents such aspyrethrum, rotenone, derris extract, nicotine, and organic thiocyanates.

Economically, my compounds possess the great advantage of remaininghighly toxic in very low concentrations. Another advantage of mycompounds, notmentionedelsewhere, isthat they do not produce-a.discoloration :of vegetables such as squash andn-cucumbers. Furthermore,.mv

5 compounds are safe; and, when it comes to performance combined withsafety, my compounds are a great improvement over similar prior artinsecticides. I claim: 1. Compounds of the general formula:

wherein R is an alkyl radical selected from the group CH3 and CaHs.

2. 2 nitro 1 p chlorophenyl 1 (2.4 dichlorophenyl) -propa.ne.

3. 2 nitro 1 p chlorophenyl 1 (2.4-dichlorophenyl) -butane.

4. An insecticidal composition comprising m from about 0.0125 to about5.0% of a compound of the general formula:

wherein R is an alkyl radical selected from the group CH: and C2H5, anda carrier therefor.

5. The composition of claim 4 where the carrier is a. petroleumdistillate.

6. The composition of claim 4 where the carrier is a. powdered aluminumsilicate.

EDWARD B. HODGE.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,397,802 Muller Apr. 2, 1946 2,516,188 Haas et a1 July 25,1950

4. AN INSECTICIDAL COMPOSITION COMPRISING FROM ABOUT 0.0125 TO ABOUT5.0* OF A COMPOUND OF THE GENERAL FORMULA: